Purdue mechanical engineering student Janette Jaques attaches a sensor to a car seat headrest mounted to a hydraulic shaker. As the seat is shaken, sensors record vibration data used to validate results from a model that simulates the vibration. (Photo/David Umberger)

You do quick mental accounting of your finances wondering how much this will cost and, why you bought such a poor quality car.

However, poor quality may not be the culprit - noise and vibration control, or lack there of, is an industry-wide problem and a major source of customer dissatisfaction. The problem may be solved, thanks to researchers at Purdue University who developed a model that could help eliminate rattling before it starts.

They created the model out of four equations that correspond to four key structural elements in the headrest. As the seat is shaken, attached sensors record vibration data. Later, a hydraulic shaker recreates the precise frequencies at which suspension and seats vibrate.

Researchers hope that determining precisely which frequencies make the headrest rattle would enable automakers to better tune suspension systems, but the current goal is to modify the headrest design. "The main objective is to develop a modeling technique so most of the design work can be done before a prototype is ever built," says one researcher.

One theory is to increase the mass of the headrest, then test that theory with the model. Because the headrest is more complex than the researchers anticipated, they have to keep the mechanism rigid enough to keep the headrest from falling, but not so rigid it can't be adjusted.

Researchers believe their modeling technique can be applied to other noisy and vibrating parts like instrument panels, seats, transmissions, suspensions, and seatbelts.